The present invention deals with a retrieval device for removing material from a body.
Biological material, such as stones, can reside at least in the kidney, ureter, or biliary duct. Stones can be extremely painful and require medical treatment. Removal of stones from the body has been accomplished by two methods in the past. The first method is stone removal through conventional surgery; a treatment with obvious disadvantages, risks and drawbacks. The second method is to remove stones under the guidance of an endoscope. In this method a grasping device is guided through the body tract to the site of the stone and is used to grasp and remove the stone under endoscopic guidance. Grasping devices which have been used in the past for the removal of stones include basket devices that have generally straight legs that bow outward from the center of the basket.
The invention provides a device and method for retrieval of material from a body. More particularly, the invention relates to a device and method for immobilizing a stone in the body with a basket of the device so the stone can be effectively fragmented and then allowing the stone and/or the pieces thereof to be removed via the basket which is formed, pursuant to the invention, of multiple, spiral-shaped, generally parallel, non-overlapping, and non-intersecting legs that are flexible and relatively closely spaced to each other (e.g., no more than about 2 mm apart).
The retrieval device of the invention includes the basket, a sheath movable relative to the basket, and a handle. The basket has spiral-shaped legs disposed around a central axis. The spiral-shaped legs have improved flexibility and moveability. In an intermediate section of the basket, the spiral-shaped legs are disposed substantially parallel to one another around the central axis. The legs do not intersect. Intersecting legs tend to restrain basket leg flexibility.
In one aspect, the invention relates to a device for retrieving material from a body. The device includes a sheath having a lumen extending therethrough and having a distal end. The device also includes a basket movable relative to the sheath from a retracted position in which the basket is withdrawn within the lumen of the sheath and an expanded position in which the basket is extended beyond the distal end of the sheath and open. The basket comprises a first portion and a second portion with two or more legs extending from the first portion to the second portion. The basket further comprises an intermediate portion between the first and second portions in which the legs are, when the basket is expanded, spirally arranged, substantially parallel, and non-intersecting. The intermediate portion of the basket is displaced radially outward relative to the first and second portions when the basket is in the expanded position. When in the expanded position, the basket can provide a support surface for the material when it is being fragmented, and it can further be used to capture the fragmented material.
Embodiments of this aspect of the invention can include the following features. For example, in one embodiment the legs of the intermediate portion of the basket may be spaced about 0.0787 inches to 0.394 inches apart. In another embodiment, an elongate member may extend within the lumen of the sheath and may be operably attached to the basket such that movement of the elongate member relative to the sheath results in the basket moving between the expanded and retracted positions.
In another aspect, the invention features a method for fragmenting and retrieving material (e.g., a stone) from a body tract This method involves inserting into a body tract a device such as the device described above. The method further includes immobilizing material in the body tract by moving the basket from the retracted position to the expanded position whereby the material is blocked, and then fragmenting the material in the body tract while using the expanded basket to limit movement of the material during fragmentation. The expanded basket can then be manipulated to capture at least some of the fragmented material within the basket. The captured fragmented material is then recovered from the body by withdrawing the device from the body tract